This invention relates to an improved tilting device for outboard engines and more particularly to an improved arrangement for suspending an outboard drive from the transom of an associated watercraft.
As is well known, a marine outboard drive, such as an outboard motor, is normally suspended from the transom of the associated watercraft for movement between a tilted down running position and a tilted up out of the water position. In addition, the supporting arrangements also permit trim adjustment of the angle of the propeller in the tilted down position. In one of the more common arrangements for supporting outboard drives for such movement, the outboard drive is supported for its pivotal movement about a single pivot axis. In this way, the propeller and propeller shaft swing through an arc when the trim and tilt angle of the motor or outboard drive is adjusted. Although such arrangements have the advantage of simplicity, they present several problems.
A problem in connection with such simple single pivot suspension arrangements for outboard drives is that the propeller extends a substantial distance rearwardly of the transom when the drive is in a tilted up arrangement. This causes the watercraft to take a much longer than normal effective length and makes maneuvering when docking and in similar circumstances very difficult. In addition, the center of gravity of the watercraft may be shifted rearwardly to such an extent as to cause the front of the hull to raise undesirably during such maneuvering. Another disadvantage with this type of arrangement, which is particularly prevalent in connection with outboard motors, is that the power unit itself is swung forwardly and encroaches over the transom into the interior area of the watercraft.
It is also known that it is desirable when accelerating to have the angle of the propeller shaft disposed at a negative degree to the horizontal and with the propeller positioned substantially below the keel line for good acceleration. However, when running at high speed, it is desirable that the propeller be substantially in line with the keel line and the angle of the propeller shaft should be in the range of 4.degree. to 10.degree. to the horizontal. The conventional single pivot axis support for outboard drives has not permitted adjustment of the drive through these preferred angle relationships.
Various linkage arrangements and suspension systems have been proposed that attempt to solve the aforenoted problems. However, of the previously proposed types of supporting arrangements, although they may solve some of the problems, they magnify others. For example, it has been proposed to provide a parallelogram linkage system for supporting the outboard drive for its movement. Such arrangements have the advantage of raising the drive more than a conventional single pivot axis arrangement, however, these systems tend to nevertheless cause the outboard drive to extend to too great a length during tilting up operation. In addition, it is also desirable to permit the outboard drive to pop up when an underwater obstacle is struck and some of the linkage systems previously proposed would not permit this movement.
It is, therefore, a principal object of this invention to provide an improved suspension arrangement for an outboard drive.
It is another object of this invention to provide a suspension arrangement for an outboard drive that will orient the propeller at the desired trim angles through its adjustment range.
It is a yet further object of this invention to provide a suspension arrangement for an outboard drive that is effective to cause the propeller to raise significantly in relation to its lengthwise extension during tilting up operation.
It is a still further object of the invention to provide an improved suspension and tilting arrangement for an outboard drive that is compact and which will permit the desired degrees of movement without encroaching in the area within the watercraft or unduly lengthening the effective length of the watercraft during tilting up operation.